— Jon Lowder usually disdains computer-generated telephone calls — “robo-calls,” he grumbles — but when he got two this week from Costco Wholesale Corp., the Winston-Salem, N.C., man didn’t mind.

The giant warehouse retailer was dialing Lowder to warn him that two brands of peanut butter sports bars he bought for his kids had been recalled as part of a growing salmonella food poisoning scare.

“They’d scoured their database and found any members who had purchased Clif Bars from them and then called them to let them know that they should dump those Clif Bars,” said Lowder, a 42-year-old marketing consultant, who bought those snacks and some Zone Perfect Bars as well. “Did I mention I love Costco?”

Federal health officials say 488 illnesses in 43 states and at least six deaths have been linked to peanut butter and peanut paste products from a Peanut Corp. of America plant in Blakely, Ga. More than 31 million pounds of peanut products are now involved in the outbreak, they said.

As the number of implicated items tops 125 in what may wind up as one of the largest food recalls ever, certain shoppers are getting personalized warnings from the stores that sold them. They’re customers who hold membership cards at places such as Costco, or “loyalty cards” used to access discounts and services at some grocery stores.

1 million calls to Costco customersAbout 1 million of Costco’s 54 million card-carrying members got calls about peanut butter products this week, said Craig Wilson, assistant vice president of food safety for the Issaquah, Wa., company.

And in the Northeast, the Wegmans regional grocery store chain completed more than 17,000 calls about potentially tainted ice cream on Tuesday, and nearly 3,000 calls about suspect peanut butter cup candy on Thursday, all to holders of the store’s “Shoppers Club” cards who bought the affected items, according to a spokeswoman.

“It was really amazing that so many customers had no idea about the recall,” said Jeanne Colleluori, of the Rochester, N.Y.-based chain.

The outreach is part of a small but growing trend that raises questions among consumer privacy advocates but draws praise from shoppers warned away from suspect products.

Last summer, 45-year-old Dorianne Steingass received a call from the Kroger Corp. as she was preparing a spaghetti meat sauce for her family. The computer warned that the meat the Miamisburg, Ohio, woman had just purchased was part of a vast recall of 5.3 million pounds of ground beef potentially contaminated with dangerous E. coli bacteria.

“I was going to give my six children the meat,” Steingrass said. "I changed my menu that night. I don't remember what we had, but it wasn't that meat."

Chalk up a victory to “relationship marketing,” in which retailers try to woo consumers with personal reasons to seek their stores. In the case of food safety outreach, it’s a win all around, said Nancy Childs, a professor of food marketing at St. Joseph’s University in Philadelphia.

“We have at risk the consumer confidence in the food supply,” Childs said. “They’ll welcome any idea that someone is looking out for them.”

Confidence comes at a costBut that confidence may come at a cost, noted Alessandro Acquisti, assistant professor of information technology and public policy at Carnegie Mellon University. He said he appreciates the constructive use of consumer data to warn about food poisoning, but worries about less benevolent actions.

“It this case, many consumers would be happy their information was used that way,” said Acquisti, “But they may be very unhappy if that same data is used to send them advertising they don’t want or if it is used in other ways they don’t want.”

A 2008 survey by the Food Marketing Institute, an Arlington, Va., industry trade group that focuses on food safety, research and education, showed that nearly half of some 87 members operating more than 16,000 stores offered frequent shopper programs.

Of those, 37 percent used the loyalty card data to alert shoppers about the details of recalled products, with most notifying only consumers who bought the affected items, the survey said.

In many places, the practice is still new. Wegmans started making calls in November 2007, just as some of the company’s ground beef was named in a recall, Colleluori said. Kroger began experimenting with calls last spring, just before the summer’s big beef recall, according to spokeswoman Meghan Glynn.

Costco started making phone calls within the last two years, after a decade of sending letters about recalled items.

The effort isn’t comprehensive. Costco makes calls only for items identified as potentially serious or deadly Class 1 recalls by federal officials. Calls can only be made to consumers who provide accurate phone numbers and, in the case of Wegmans, only those who provide landlines. That company will try the call three times before giving up, Colleluori said.

Even now, most consumers who shop at Kroger or affiliated stores such as Ralph’s, Fred Meyer or QFC are warned only through “receipt tape notification,” Glynn said. In that program, shoppers who buy recalled products learn about it only the next time they swipe their cards, when a note at the bottom of the receipt will alert them that they should discard the item.

“This is a new world for us,” Glynn said. “We’re still working on it.”

Most consumers are surprised to receive individual alerts about recalled food, store officials said. Lowder, the North Carolina father, said he appreciates the notification, especially in a time when food recalls seem to be increasing.